The present invention relates generally to optical communication systems and, more particularly, to an integrated optical transducer assembly for high speed, parallel optical communication data links.
There are many well-recognized benefits of using optical fiber to replace copper wiring for printed circuit boards (PCBS) in high speed electronic systems such as computer systems, switching systems, and networking systems. Such potential benefits include increased bandwidth and data rate, overcoming bottlenecks in the processing architecture, immunity to electromagnetic interference and reductions in radiated electromagnetic noise from the system, reduced latency by placing optical/electrical (OLE) conversion as close as possible to the signal originating circuits (e.g., computer processors) in order to minimize electrical attenuation, more dense packaging at lower cost per pin, and enablement of new processor interconnect technologies such as meshed rings. These and other factors directly contribute to the performance of the computer system (e.g., increased processing power in MIPS (million instructions per second) or FLOPS (floating-point operations per second), increased node count in parallel architectures, etc.).
With the dramatic increase in processor speed over the last several years and the anticipation that this trend will continue, the copper interconnect technology will be unable scale to the bandwidth requirements of the processing units, especially for large symmetric multi-processing (SMP) systems. Fiber optic components, on the other hand, do not suffer from bandwidth/distance constraints of copper and are thus becoming a preferred medium for very high bandwidth transmission between high speed electronic (e.g., processing) units. But, in order to fully realize these benefits, the optical fiber interconnect components should also continue to provide the same benefits of the existing electrical connection technologies.
At present, conventionally fabricated optoelectronic transducers typically include light emitting devices such as a Vertical Cavity Surface Emitting Laser (VCSEL) configured in a laser array, as well as light detecting devices such as photodiodes configured in a photodiode (PD) array. In addition, supporting high speed circuits (e.g., fabricated from a silicon bipolar, SiGe or GaAs material) are used to condition a signal when driving a VCSEL or receiving a signal from a PD. Such devices are typically disposed on a printed circuit board along with the computer circuits. Because a VCSEL array is generally formed of a different material than silicon, the array may not match thermally with preferred substrate materials. More specifically, there generally is a thermal coefficient of expansion (TCE) mismatch between the optical device material and the substrate material. As such, this physical limitation does not allow for a significantly large array of VCSELs (fabricated within a GaAs chip) to be placed on a silicon, organic, or ceramic substrate. Without a sufficiently large VCSEL/PD array, the high density signal requirements for complex processor interconnects are not met. Accordingly, it would be desirable to be able to be able to configure larger arrays of VCSEL devices and/or PD devices on a substrate even if there are TCE mismatches therebetween.